Most international students panic at the wrong number. They see a Turnitin similarity score of 18% and assume they are about to be reported for plagiarism — when in reality the percentage is only the start of the story, not the verdict.
Most international students panic at the wrong number. They see a Turnitin similarity score of 18% and assume they are about to be reported for plagiarism — when in reality the percentage is only the start of the story, not the verdict. This guide answers the questions Vietnamese students ask MAAS mentors most often when a similarity report lands in their inbox the night before a deadline.
Author: MAAS Editorial Team · Reviewed by a MAAS Academic Integrity Advisor (PhD, with university marking experience)
Last updated: 2026-06-05
Category: writing-tips
What does the Turnitin similarity score actually measure?
Direct answer: The similarity score is the percentage of your text that matches sources in Turnitin's database — other student papers, journals, websites, and books. It measures text overlap, nothing more. It is not a plagiarism score, not a measure of how much you copied, and not a pass/fail judgement. A high score can be entirely innocent (quoted material, reference lists, common phrases) and a low score can still hide genuine plagiarism if someone paraphrased badly without citing.
Evidence: Turnitin's own guidance states explicitly that the Similarity Report "does not check for plagiarism" — it identifies matching text and leaves interpretation to the instructor. The percentage is generated by their matching algorithm; the academic judgement is human.
Example: A Vietnamese Business student at RMIT came to a MAAS advisor terrified of a 31% score. Reviewing the report together, 22 of those percentage points were her correctly quoted and cited interview transcript plus the reference list. The genuinely overlapping text was under 9%, all properly attributed. The "scary" number was an artefact of how the report counts quotes — not a problem at all.
Is there a single "safe" similarity percentage?
Direct answer: No — and anyone who gives you a fixed number is misleading you. There is no universal threshold. Different universities, faculties, and even individual markers set different expectations, and the rubric usually matters more than any percentage. As a working orientation many UK and Australian markers grow more attentive above roughly 15-20%, but a 25% report made entirely of cited quotes is fine, while a 10% report built from one uncited paraphrased paragraph is a real integrity problem.
Evidence: Most university academic-integrity pages refuse to publish a "safe" cut-off precisely because it invites students to write to a number instead of writing honestly. The University of Melbourne and the University of Manchester both state that similarity percentage alone does not determine misconduct — the source and context of each match does.
Example: A Vietnamese postgraduate at the University of Leeds asked her MAAS mentor to help her get "under 10%." The mentor reframed the goal: instead of chasing a number, they audited each match. Two matches were uncited paraphrases — a genuine issue they fixed by adding citations and rewording in her own voice. The final score was 14%, higher than her target, but every match was now legitimate and defensible.
Which matches are normal and which ones are warning signs?
Direct answer: Normal matches are quotations you cited, your reference list, technical terms, standard methodology phrasing, and the assignment question itself. Warning-sign matches are long continuous strings from a single source, paraphrases close to the original with no citation, and matched text that you do not recognise. The skill is reading the colour-coded report match by match, not staring at the headline percentage.
Evidence: Turnitin breaks the report into individual sources ranked by contribution. Their documentation recommends reviewing each match's source and context rather than the aggregate figure — which is exactly how experienced markers read it.
Example: A Vietnamese Engineering student at Monash had a single 14% match to one website. That concentration — one source, one long block — is the pattern markers worry about. His MAAS advisor showed him the block was an uncited definition he had pasted as a placeholder and forgotten. He rewrote it in his own words and added the citation; the concentrated match disappeared.
Why does my reference list or quoted material inflate the score?
Direct answer: Turnitin matches everything by default, including your bibliography and direct quotes, because they are by definition identical to the source. This routinely adds several percentage points that have nothing to do with originality. Most instructors exclude quotes and bibliography when interpreting the report, and Turnitin offers filters to do exactly that — but the raw score you see first often includes them.
Evidence: Turnitin provides built-in filters to exclude quotes, bibliography, and small matches under a set word count. When these filters are applied, similarity scores commonly drop by 5-15 percentage points with no change to the actual writing.
Example: A Vietnamese Law student at the University of Sydney saw 27% and assumed the worst. Her MAAS advisor applied the standard quote-and-bibliography exclusion filter while reviewing the report; the score fell to 12%, all of it correctly cited case law. Nothing in her writing changed — only how the report counted standard legal citations.
What should I do if a match is genuine?
Direct answer: Fix it properly, do not try to trick the detector. If text is too close to a source, do two things: cite the source, and rewrite the idea in your own words and sentence structure so it reflects your understanding rather than a thin disguise of the original. The goal is genuine paraphrasing — restating an idea you understand — not running text through a spinner to fool the algorithm, which produces unreadable prose and is itself an integrity violation.
Evidence: University academic-integrity policies treat "patchwriting" — swapping a few words while keeping the source's structure — as a form of plagiarism even when a citation is present. Proper paraphrasing requires both attribution and genuine restructuring, a distinction every integrity policy makes.
Example: A Vietnamese Education student at the University of Auckland had three paraphrased paragraphs flagged. Rather than reword them mechanically, her MAAS mentor walked her through the underlying argument until she could explain it in her own words, then she rewrote each paragraph from her understanding and added the citation. The rewrites read better and matched honestly — because they were genuinely hers.
How can I avoid integrity problems before I ever run a report?
Direct answer: Cite as you write, never as an afterthought. Keep quotation marks around anything copied verbatim the moment you paste it, log the source immediately, and paraphrase from your understanding rather than from the source text sitting open beside you. If you build the habit of attributing sources during drafting, the similarity report becomes a confirmation step rather than a crisis.
Evidence: Writing-centre research consistently finds that most student plagiarism is accidental — lost citations, forgotten quotation marks, and source text copied as a "placeholder" that never gets rewritten. Process habits prevent the overwhelming majority of integrity flags before any detector is involved.
Example: After one stressful report, a Vietnamese Marketing student at RMIT adopted a simple rule from her MAAS advisor: every pasted sentence gets quotation marks and a source note in the same keystroke. Her next three assignments came back with clean, fully-attributed reports — and she stopped dreading the submission button.
Frequently asked questions
Is a 20% Turnitin score bad?
Not necessarily. If those 20 points are cited quotes, your reference list, and standard phrasing, it is fine. If even 5% is uncited paraphrase from one source, that is the real problem. Read the report match by match, not by the headline number.
Does Turnitin detect paraphrasing?
It detects paraphrasing that stays close to the source wording or structure (patchwriting). Genuine paraphrasing — where you restate an idea you understand in your own structure — produces little to no match. The fix for flagged paraphrase is to understand the idea and rewrite it, plus cite.
Will quotes and my bibliography count against me?
In the raw score, yes, because they match their sources exactly. Most instructors apply Turnitin's filters to exclude quotes and bibliography when interpreting your report, which usually lowers the score noticeably.
Can I lower my similarity score by using a paraphrasing tool?
Disguising matches with a spinning tool is itself an integrity violation and usually produces unreadable text that markers spot instantly. The legitimate way to reduce a genuine match is to cite the source and genuinely rewrite the idea in your own words.
Can MAAS help me understand my Turnitin report?
Yes. The Academic Integrity Check provides a plain-language interpretation of every flag, an action checklist of what to fix versus what is already fine, and optional formatting and proofreading on your own draft — an audit of your work, not a rewrite of it.
Related resources
- Academic Integrity Check service — Turnitin similarity + AI-detection interpretation and a pre-submission audit of your own work
- Why your own writing gets flagged as AI-generated — the companion guide on AI-detection false positives
- Using AI ethically in a literature review — where AI assistance is legitimate and where it crosses the line
- How to write a methodology section examiners believe — originality starts with genuinely your own research design
- Academic Support service — full Outline → Draft → Final mentoring, with the guidance of a MAAS expert
Worried about a similarity report before you submit? Book a free consultation — a MAAS advisor will read the report with you and help you remediate your own work in line with your institution's integrity policy.
This article is academic-integrity guidance and does not replace your own work or your institution's policy.